Now, start as before, by making an overall mid-value shape, with the lights reserved as white shapes. This time, though, allow the middle value area to be more subtle and complex. While the wash is still wet, make graded transitions from middle toward dark (but save the very darkest darks for a second layer). Add color, if you like, such as the pink and yellow and green in the bottom image here. Finally, apply the darkest darks, like the doors and the tire in the top image, below. Use one of these photos, or one of your own.
In all three of the above images, the darks are mostly distinct, hard-edged shapes. They give final definition to the middle value shapes and the lights. The pink and green in the bottom image, for example, could have been applied very casually, and the darks would clarify their identities and locations.